Assuming you have the premium version of rom manager as well, go into RM and press the menu button to bring up the settings, and enable advance mode, once that is done try going into Downloads, and you will see different roms to choose from, I personally suggest reading up on the above overclocking link and reading on the forums on each rom developer and then when you feel ready, choose a rom in a RM and enjoy all of the rootness glory, personally I love Lithium Mod, and you can add a 800mhz kernal to your phone as an option when your using LM, but every rom offers that as well, its kind of a standard